mplayer: start track IDs from 1 rather than 0

Completely pointless, but makes ChrisK happy for some reason.

Track ID 0 is now rejected by the option parser itself.
options: replace --edition=-1 with --edition=auto

Originally, the objective of this commit was changing --edition to be
1-based, but this was cancelled. I'm still leaving the change to
demux_mkv.c though, which is now only of cosmetic nature.
mplayer: replace "D:" in status line with "Late:"

Too many people thought "D:" really meant number of dropped frames. But
it's actually the number of frames where the playloop thought it'd be
a good idea to drop them. Of course this does nothing if frame dropping
is disabled, but even with normal frame dropping, this doesn't indicate
whether a frame was _really_ dropped. (Looks like libavcodec doesn't
even give us this information reliably? The decode function can return
no frame in case of codec delay due to threading and such.)